- The Sepolia testnet will undergo a post-merge execution layer (EL) upgrade to the block 1735371expected August 17, 2022
- The upgrade will cause EL clients on the network to be disconnected from peers who have not moved to proof-of-stake. It doesn’t add any additional features beyond that.
- Sepolia node operators must upgrade their execution layer client before blocking 1735371.
- A similar upgrade is expected on Goerli and the Ethereum mainnet once these networks move to proof-of-stake.
Background
In order to maintain a healthy peer list, Ethereum execution layer nodes will automatically disconnect peers that do not have the same upgrade sequence as them. On the Ethereum mainnet, this means checking if a peer has upgraded to Thawing of borders at block 200,000, then Property at block 1,150,000, and so on until the last upgrade, Glacier Graywhich happened at block 15,050,000. EIP-2124 specifies how this is managed. In typical network upgrades, which are triggered by a block height, this happens automatically when nodes use the block height of upcoming upgrades to filter their peers.
For The Merge this was not possible because the upgrade was triggered using a total difficulty value rather than a block number. The rationale for this choice is explained in EIP-3675:
Using a predefined block number for the hardfork is dangerous in this context because the choice of PoS fork takes priority during the transition.
An attacker can use a minority of hashing power to create a malicious chain fork that would satisfy the block height requirement. Then, the first PoS block can be maliciously offered on top of the PoW block from this adversary fork, thus becoming the head and compromising the security of the transition.
To protect the network from this attack scenario, the chain’s accumulated difficulty (total difficulty) is used to trigger the upgrade.
To minimize changes to the protocol during its most complex upgrade since launch, The Merge’s design excluded EIP-2124 compatibility. This means that an additional upgrade now needs to be done to add this. It is important to note that the only change introduced as part of this upgrade is to specify a block number that nodes can use to identify peers that have gone through The Merge. No other features are being introduced or deprecated as part of this upgrade.
Upgrade Information
Timing
This upgrade will take place on Sepolia at the block 1735371expected August 17, 2022.
Note that a similar upgrade will be announced for Goerli and mainnet after these networks transition to proof-of-stake.
Ropsten goes not be upgraded as it is now considered obsolete, along with Rinkeby and Kiln. See this message for more details on their depreciation schedule.
Client versions
Only runtime layer clients need to be updated for this upgrade. Node operators can continue to run their current version of the consensus layer client on Sepolia during the transition.
Note that the client versions used for the Görli/Prater merge all supports this upgrade on Sepolia. In other words, if you have already downloaded a version for the Goerli/Prater merger, you can use that same version on Sepolia for this upgrade.
Execution layer
Upgrade Specifications
The specification of this change is followed as part of the Paris specifications, under the FORK NEXT upgrade section.
FAQs
As a node operator, what should I do?
You must upgrade your runtime layer client to one of the versions listed above before August 16, 2022. Your consensus layer client does not need to be upgraded.
As a player, what should I do?
The validator set to Sepolia is authorized. If you are a current Sepolia validator, you must update your runtime layer client to one of the versions listed above no later than August 16, 2022.
If you are not part of the current set of Sepolia validators, you do not need to do anything at this time.
Goerli/Prater validators and mainnet will need to follow the same steps when this upgrade is announced on these networks.
As an application or tool developer, what should I do?
Nothing, unless you also run a node. If so, please upgrade your runtime layer client to one of the versions listed above before August 16, 2022.
As an Ethereum user or Ether holder, do I need to do anything?
No. The Ethereum mainnet is not affected by this upgrade. Even when this upgrade is applied to the mainnet, no action will be necessary.
Thanks to Justin Chrn for the original cover image and Tomo Saito for the modifications.
